Providing telephone communication services to multiple passengers of airplanes has become common. Prior art systems use on-board equipment (i.e.,equipment co-located with the airplane) which provides multiple communication channels between the airplane and a ground-based antenna which is in range of the airplane. The ground-based antenna is connected to a Public Switched Telephone Network (PSTN) which provides communication services to ground-based telephony equipment. Ground-based antennas can be linked together over terrestrial hard-wired links or though satellite links (e.g., geosynchronous satellite links).
One prior art, airplane communication system pre-assigns a "user code" or "personal identification number" (PIN) to passengers who might want to use on-board communication resources during their flight. The user code or PIN is assigned to a passenger before the passenger embarks. The passenger can disseminate the user code to any person who might want to reach the passenger during the flight. To register with the system or to place a call during the flight, the passenger enters the pre-assigned user code into the seat back handset.
The system checks a registration database to determine the airplane's location and the seat at which the passenger is located. After the system identifies the airplane's location and sends a message to the airplane via an in-range ground-based antenna, the passenger's seat back handset notifies the passenger of the incoming call.
For a ground-to-air call, a person wishing to contact the passenger during the flight (referred to herein as a "ground calling party") can do so by dialing a central system number (e.g., a "1-800" number), entering the passenger's pre-assigned user code, and entering the ground calling party's phone number. The system then contacts the passenger and, if the passenger accepts the call, the system calls the ground calling party back. The process of first calling a central number and being contacted by the system in a second, return call is referred to as "two-stage dialing with callback".
Several aspects of this prior art system are inefficient and make using the system inconvenient for both the passenger and others who wish to contact the passenger. For example, each airplane communication system has a number of available communication numbers which it can allocate to passengers. The airplane communication system must register and occasionally re-register every available number, whether or not the numbers are actually used by passengers. Registration and re-registration traffic consumes large amounts of system resources.
In addition, as explained previously, the prior art system uses two-stage dialing with callback, which is less convenient than if the ground calling party could directly contact the passenger using a single phone number. In addition, the prior art system does not accommodate passengers who do not have a pre-assigned user code or PIN. The requirement of the pre-assigned user code is also undesirable because the ground calling party must have knowledge of the user code in order to contact the passenger.
A group of co-located passengers traveling in a common vehicle (e.g., an airplane, bus, ship) are referred to herein as a "mobile user group" or "co-located mobile users". Where there are mobile user groups, it is desirable to be able to serve tow groups of passengers, i.e., those that have PIN cards and those that do not. In addition, where the communications link between passengers in a vehicle and non-passengers is a satellite link, only a limited number of communication channels may be available for use.
What is needed is a method and apparatus which reduces the quantity of registration traffic, allows direct inward dialing to a passenger during ground-to-air call attempts, direct outward dialing by passengers, and minimized loading on the system.